nytimes 1.25.07 / three years ago, jason beukema, a tour manager at a travel agency in atlanta, thought he was just doing his friends a favor in organizing a group vacation. little did he know that the music-themed cruise he created would blossom into a full-fledged business. what started as a few close buddies grew into 125 friends and acquaintances boarding what he called the groove cruise in october 2004. "all of a sudden people who'd heard about it from their friends just started calling me, wanting to find out about the cruise," said mr. beukema, who started whet travel after returning to atlanta from the first voyage. "we didn't spend a dime on advertising. it was all word of mouth." on a recent groove cruise, aboard the freedom of the seas, somewhere between grand cayman and jamaica, 200 young professionals decked out in silk robes and slinky lingerie were poolside long after the casino had closed and the other sunburned passengers had turned in for the night. vodka red bulls and glowsticks in hand, the mostly barefoot crowd danced to the sensuous vocals and dirty bass pumping from the speakers. "now this is a party," yelled kathy hirsecorn, 29, her pink satin negligee fluttering as she danced. "you forget you're on a boat." part of a larger resurgence of affinity voyages, music-themed cruises are growing in popularity as third-party promoters and cruise line executives seek to capitalize on large fan followings with the time and cash to spend on a vacation with their favorite musicians. devotees have packed cruise ships to see artists ranging the fm dial, from mainstream stars like lynyrd skynyrd and kenny chesney to blues and christian bands, and the list of musicians scheduled to set sail is growing. yet those cruises attract a largely older audience, while the groove cruise, with its allure of club-heavy house music and high maintenance hedonism, attracts primarily dance fanatics who have graduated from college in the last 15 years and who can afford $1,350 for a five-day voyage (and $600 for a three-day cruise). "it's like spring break for adults," mr. beukema, 29, said. while the company also handles other vacations like destination weddings and bachelor party trips, its main focus is the groove cruise brand, which yields around 90 percent of the company's revenue, he said. since the first voyage in 2004, revenue has doubled each year, to $500,000; the number of attendees has tripled, to over 1,100 total participants over that period. these dance-obsessed cruisers have come from across the united states, europe and australia - 65 percent had never been on a cruise before; more than a third were returning for another spin on the groove cruise. "traditional cruises have very few alternative entertainment options for young people," said mr. beukema, who has been on 26 cruises. "if you don't want to see the broadway revue or the magic show revue you're pretty much out of luck, and the on-board nightclub has a request d.j., so you'll hear one hip-hop song and then he'll kill the dance floor with the macarena. we bring on some of the best d.j.'s from across the country and go all night." despite hurricanes, high gas prices and cheap airfare, the cruise industry made $16.2 billion in united states revenue in 2005, a 10 percent increase from the previous year. once the traditional vacation choice of the "nearly dead and newly wed," the cruise industry has been working feverishly over the last decade or so to revamp its image and attract a younger, more active market. "the cruise industry is changing their product for younger people," said joe goldblatt, senior lecturer at temple university's school of tourism and hospitality management. "gen x-er's are taking more two- and three-day vacations multiple times a year. three-day cruises are ideal for that - you board on friday, party hard all weekend and can return to work on monday." it is a formula that works well for mr. beukema, who moved whet travel from atlanta to south beach last april to be closer to the industry as well as the lavish nightlife that inspires his company's vacations. from his condo, mr. beukema works with 72 affiliates in cities nationwide to spread the word about the groove cruise. the company's web site, whettravel.com, tracks marketing and booking data for the various travel agents, nightlife promoters, magazines and radio stations that market the growing brand. groove cruise parties have been held at major nightclubs across the country, from miami to chicago to san diego, often in conjunction with the d.j.'s who perform on the voyages. this success has not gone unnoticed by other companies hungry to appeal to the groove cruise niche. perrier sponsored the last voyage, and wet grooves, a national pool party company, and overtime sports, a miami-based athletic social network with 75 young professional leagues, are co-branding with the groove cruise on promotions and future on-board activities. at night, while the rest of the cruise passengers sleep, gamble or drink, the groove cruise throws private parties with themes like "office ho's and c.e.o.'s" and "pajamas in paradise" that often don't end until sunrise. "i would wake up, head to the pool, start drinking, take a nap, eat, start drinking again and dance all night," said ted paizis, 26. "then i would do it all again the next day." the global appeal and profitability of electronic music is a key element of the company's plans, which include a european groove cruise in 2008 and fully chartered caribbean cruises after that. but if anything, customer service is the key to the company's success. "on every cruise people come up to me and tell me this is the best vacation of their lives," mr. beukema said. "it's an amazing feeling to know i'm making people happy, and it's what drives me everyday, toward the next voyage."